Looper mechanism for sewing machines



Aug. 6, 1963 N. P. LEES 3,099,973

LOOPER MECHANISM FOR SEWING MACHINES Filed Sept. 19, 1961 E: uni IE} ill 5947 INVENTOR. Nathaniel Lees WITNESS We? @W ORNE Y United States Patent Jersey Filed Sept. 19, 1961, Ser. No. 139,096 Claims priority, application Great Britain Aug. 19, 1961 Claim. (Cl. 112-199) The present invention relates to a looper mechanism for sewing machines and particularly for a small, inexpensive, hand-driven sewing machine of the type designed for use by children.

The object of this invention is to provide such a looper mechanism which is very inexpensive and which is effective, reliable, durable and efiicient bearing in mind the ultimate use of the machine by children.

Having in mind the above and other objects that will be evident from an understanding of this disclosure, the invention comprises the devices, combinations and arrangements of parts as illustrated in the presently preferred embodiment of the invention which is hereinafter set forth in such detail as to enable those skilled in the art readily to understand the function, operation, construction and advantages of it when read in conjunction with the accompanying drawings in which:

FIG. 1 is a vertical sectional view longitudinally of a sewing machine embodying the present invention.

FIG. 2 is a fragmentary sectional view substantially on the line 2-2 of FIG. 1.

FIG. 3 is a detail sectional view substantially on the line 3-3 of FIG. 1.

With reference to the drawings, there is illustrated a sewing machine having a frame consisting of a bed 1, a standard 2, and a bracket arm 3 that terminates in a head 4. A base 5 is secured to the bed 1 to add weight and thereby stabilize the machine in operation. A sheet metal bed plate 6 overlies the bed 1 and defines the work supporting surface of the machine.

Journaled longitudinally of the bracket arm 3 is a main shaft 7 upon which is mounted a gear 8 that meshes with an internal gear formed as a part of a hand wheel or crank 9 that is mounted upon a shaft 10 journaled in the upper portion of the standard 2. The hand wheel 9 has a handle 11 for rotating the same and thereby driving the main shaft 7. Journaled in the bed 1 on an axis parallel to the axis of the main shaft 7 is a bed shaft 12 which is connected for unitary rotation to the main shaft 7 by a belt 13 and pulleys 14 and 15.

The stitch forming mechanism of the machine consists of a needle 16 and a nodding-type looper 17 that coop erates therewith in the format-ion of single thread chain stitches. The needle 16 is carried by a needle bar \18 mounted in the head and for endwise reciprocation and actuated by a crank 19 mounted on the end of the main shaft 7 and having a crank pin 20 that extends into a slot in a. bracket 21 secured to the needle bar 18.

The looper 17 is formed from sheet material and comprises a looper blade 22 and a cam follower arm 23. The looper is secured to a hub 24, which, to provide for oscillation, is mounted on a fulcrum-stud or looper shaft 25 that is journaled in the bed 1. The looper shaft 25 is held against endwise movement by means of a flange 26 and a collar 27. The hub 24 is adjustable endwise and angularly of the looper shaft 25 to position the looper blade sidewise relatively to the needle, and is secured in adjusted position by a set screw 28.

Oscillation is imparted to the looper by means of -a cam 29 having a first cam surface 30 that engages the edge of the looper blade 22 and is adapted to ivot the same in one direction about the axis of the looper shaft ice 25. The cam 29 also includes a second cam surface 31 which is engaged by the arm 23 on the opposite side of the bed shaft 1-2 from the point of engagement of the cam surface 30 with the looper blade 22 and is thus adapted to pivot the looper blade 22 in the opposite direction about the axis of the looper shaft 25.

The specific configuration of the cam surface 31 is determined by the desired motion of the looper blade 22. The cam surface 30 is complemental to the cam surface 31, that is, the configuration of the cam surface 30 is such that the cam surfaces 30 and 31 and the looper blade 22 and arm 23 are constantly held in engagementthe cam surface 31 acting to drive the looper 17 pivotally during the advance or loop seizing stroke thereof and the cam surface 30 acting to drive the looper pivotally during the return stroke thereof. Thus, the looper 17 is positively driven in both directions and is positively controlled at all times.

The looper shaft 25 is shown as comp-rising a fulcrum stud journaled in the bed 1 and, as mentioned above, is confined against endwise movement by the flange 26 and the collar 27. The looper 17 is adapted to be placed upon the exposed end of the fulcrum stud 25 and locked in proper stitch-forming relation with respect to the needle 16 by means of the set screw 28. The advantages of this looper support is that by having the fulcrum stud 25 journaled in the bed 1 a good bearing support is provided for the stud, and the looper can be very easily removed from the stud and replaced by a new one should the old looper become damaged by, for example, rough handling by the child operating the machine. In replacing the looper it will be understood that the complemental cams automatically properly time the looper with the needle and the only adjustment that is necessary is the proper positioning of the looper sidewise of itself relatively to the needle. If necessary, timing of the looper with respect to the needle can be accomplished by adjusting the earn 29 on the bed shaft 12. It will be apparent from the foregoing description that the present invention contemplates an improved looper mechanism in which the looper is adapted to be mounted on the exposed end of a fulcrum stud and pivoted about the longitudinal axis of the stud by a cam arrangement also mounted on the exposed end of a bed shaft which actuates the feed mechanism as well as the looper mechanism.

Numerous alterations of the structure herein disclosed will suggest themselves to those skilled in the art. However, it is to be understood that the present disclosure relates to a preferred embodiment of my invention which is for purposes of illustration only and not to be construed as a limitation of the invention. All such modifi-cations which do not depart from the spirit of the invention are intended to be included within the scope of the appended claim.

Having thus set forth the nature of the invention, what I claim herein is:

In a sewing machine having a frame including a bed, a bed shaft journaled for rotation in said bed, and stitch forming mechanism comprising a needle bar mounted in said frame and carrying a needle and a nodding type looper cooperating with said needle in the formation of single thread chain stitches, said looper comprising a looper blade and a cam follower arm formed from a single piece of sheet metal, means for mounting said looper in said bed for pivotal movement about an axis parallel to the axis of said bed shaft comprising a fulcrum stud having an exposed end and a hub to which said looper is secured and which is mounted upon the exposed end of said fulcrum stud, and means for imparting oscillation to said looper comprising a cam, said bed shaft having an exposed end, means for securing said cam upon the exposed end of said bed shaft for rotation therewith, said cam having a first cam surface engaged in tracking relation .by said loop-er blade for imparting pivotal movement to said looper in one direction and having a second cam surface disposed axially with respect to said first cam surface and engaged in tracking relation by said cam follower arm for imparting pivotal movement to said looper in the other direction, said cam follower arm being arranged to engage said second cam surface at a point diametrically on the opposite side of said bed shaft from the point of engagement of said looper blade and said first cam surface, said cam sur- .4 faces being complemental and providing a positive drive for said looper in each direction of pivotal movement.

References Cited in the file of this patent UNITED STATES PATENTS 349,844 Harlow et a1 Sept. 28, 1886 924,903 Hemleb June 15, 1909 1,825,513 Ericsson Sept. 29, 1931 FOREIGN PATENTS 651,392 France Oct. 9, 1928 634,159 Great Britain Mar. 15. 1950 

